Tuesday 14th August 2018,

# Calculating 1RM; Alternative Methods

Paul Keepax September 18, 2012 Exercise Comments Off on Calculating 1RM; Alternative Methods

## For years now many people have used the value of their ‘one rep max’ (1RM) as a guide to how much weight to lift when doing various exercises, but is all this necessary, and is there a more straightforward and efficient way to figure out which plates to stick on the bar?

We already looked at one basic method for calculating your 1RM – how else can we measure the one rep max and why would we want to think about alternatives? Let’s take a deeper look…

A 1RM is of course the maximum that one can lift with one single effort. For example, if your best lift is 100kg then you ought to be doing 10 reps with around 75% of this weight, or 75kg for the mathematically challenged.

You can even download a chart that help you to determine either how much you ought to try lifting for any given number of reps, or conversely what your predicted 1RM should be according to how much you can lift over a given number of reps.

In other words, if you can squeeze out six reps at 100kg then your one-rep max ought to come in at round 120kg. Some particularly keen folks have even adapted the tables to suit the variable rates of drop off that occur across the different lifts but even with this, how efficient is this system, and is there a better way?

Assuming that we’re going to adapt our training according to whatever our 1RM is our immediate problem lies in actually finding this value out, especially for beginners. Aside from the obvious increase in risk from lifting an unusually heavy weight, when you make your first try (even if you are successful) you effectively and immediately invalidate your ability to determine your actual 1RM. Fatigue has to ensure that you will be at least a tiny bit depleted for any subsequent lifts.

The second consideration for using a 1RM to determine what weight you ought to be lifting is the different benefits associated with completing a different number of reps.

Regular practitioners of the single best effort (typically competitive weightlifters) will be looking to develop their absolute strength, whilst those looking for hypertrophy will typically find themselves performing a lot more reps.

The essential training theory of ‘specificity’ will ensure that those who train with higher reps will improve at lifting higher reps, whilst those that lift fewer reps with a heavier weight will get better at that. There will be a little crossover, but if you only try for a 1RM sparingly then you won’t improve at 1RM as much as you will if you train at say, 10RM.

In the same way, a 10k runner wouldn’t use his 100m PB to calculate his training pace over 10K either. He might do a few sprints from time to time as part of his programme, but he’ll know that the vast majority of his 10k improvement will come from training at distances that are much, much further than 100m.

All this may seem a little pedantic and over critical, until one considers that there might be a far easier way to calculate how much weight one ought to be lifting.

If, for example you want to know what your 10RM is then just do 10 reps, try for 11 and if you’re unsuccessful then you’ve found your 10RM! Better still, just set yourself a rep range – 8 to 12 works well in this example. Whenever you can manage 12 with good technique and no more than one or two ‘technically imperfect’ reps (if your technique is 100% perfect then you’re probably not lifting heavy enough), then move the weight up by the smallest available margin for the next session and try and do at least 8. If you can’t manage 8 reps then the weight is too heavy, so drop it back next time.

Write it all down, and if/when you want to train for a different type of benefit just use a different rep range (3 to 6 for strength or 12-16 for muscular endurance) but use the same parameters to operate, albeit with a lower tolerance for dodgy reps on lower rep ranges.

It’ll take you a maximum of two sessions to determine where you should be, but you’ll always have a new target for every session and you’ll be sure to fully overload your muscles every time; which is where the real benefits will come from whatever your weight training goal is.